Major depression in later life is common, especially in primary care settings, where the six-month prevalence is 6-10%. It undermines treatment adherence and amplifies the disability associated with co-existing medical (e.g., hypertension and diabetes) and psychosocial (e.g., bereavement) problems. It is associated with high rates of morbidity and mortality. Because treatment is only partially effective, reflecting both social inequalities in outcomes of depression-treatment and particularly difficult mental health-care disparities affecting older African Americans, preventing depression in later life should be an important public health priority. Based upon the Institute of Medicine's framework for prevention of mental illness, we propose to conduct a study of "indicated preventive intervention" in black and white people aged 50 and older who are already symptomatic but not clinically depressed. We hypothesize that the use of Problem-Solving Therapy for Primary Care (PST-PC), which is tailored to address specific risk factors for depression (e.g., insomnia, bereavement, disability related to medical illness, and isolation) and which has been shown to be acceptable to older African American patients in primary care, will be superior to an attention-only, supportive control condition (providing education in health dietary practices: DIET) in lowering the incidence of major depressive episodes over two years and improving health-related quality of life. We will recruit 306 subjects (153 black and 153 white) from the Center for Minority Health's Healthy Black Family Project (HBFP) and from primary care practices in Pittsburgh affiliated with the Coordinated Care Network. We will randomly assign them to either PST-PC (n = 153) or to DIET (n = 153), stratifying by race. Both interventions (PST-PC and DIET) are manualized and consist of 6-8 brief sessions, totaling 5-7 contact hours, distributed over 6-12 weeks, followed by brief maintenance booster sessions at 6, 12, and 18 months. They will be delivered onsite at HBFP and at CCN practices. PST-PC, which has been shown to be an effective treatment for older black and white people living with major depression, teaches them to regain a sense of control ("self-efficacy") through a structured process of problem-definition, goal-definition, generation of potential solutions, evaluation and choice of solutions, and practice with implementation. DIET teaches healthy eating practices and provides education about nutrition;it is a plausible, culturally appropriate, and potentially beneficial health-promoting intervention in its own right. Participants will be assessed every three months over a two-year follow-up period by raters blind to randomized intervention assignment. Efficacy will be assessed via survival analysis of rates of incident major depressive episodes and time to episode;and by random regression analyses of measures of depressive symptoms and health-related quality of life over two years. This information will help to establish whether PST-PC is a useful strategy for indicated preventive intervention for major depression in black and white people aged 50 and older, thereby overcoming mental health care disparities and improving the health of older people.